1. Field of the Invention
The present invention relates to an ignition coil that applies voltage to an ignition plug for an internal combustion engine, and relates to a manufacturing method for manufacturing the above ignition coil.
2. Description of Related Art
A conventional method for molding a resin molded body having a coil body embedded therein during the manufacture of an ignition coil has been known (see, for example, JP-A-2003-243236). Specifically, in the above molding method, a coil body, which has at least a primary coil and a secondary coil, is placed in a cavity of a die, and then a resin material, which is in a liquid or melted condition, is introduced into the cavity such that the resin material is cured to be hardened.
When the resin molded body of JP-A-2003-243236 having the coil body embedded therein is molded, the resin material is introduced into the cavity by a sufficient pressure such that the resin material is uniformly filed into an entirety of the cavity in a short time. Thus, in order to improve the productivity, it is important to place the coil body at a position in the cavity for limiting the displacement of the coil body due to the pressure during the introduction of the resin material.
In the above, the coil body of the ignition coil of JP-A-2003-243236 is not provided with a positioning portion that is configured to position the coil body in the cavity. Accordingly, in the manufacture of the above ignition coil of JP-A-2003-243236 having the coil body, in which a center core wounded with a primary coil is exposed to an exterior of the resin molded body, the center core is assumed to be held between dies for positioning the coil body in the cavity. However, in the above ignition coil, the center core made of a magnetic material, which core is exposed to the exterior of the resin molded body, may rust after the molding, and thereby performance degradation of the ignition coil may be caused. Therefore, there has been needed improvement.